1. Field of the Invention
The present invention relates to a vibration wave linear motor and lens implement using the vibration wave linear motor which implements ultrasonic vibrators, and in particular, a vibration wave linear motor and lens implement using the vibration wave linear motor with a simple configuration that can be miniaturized.
2. Description of the Related Art
In recent years, attention has been focused on ultrasonic motor (vibration wave motor) as a new motor to replace electromagnetic motor. This ultrasonic motor has advantages such as the following, in comparison to the conventional electromagnetic motor:
namely, (a) obtain high thrust at a low speed without a gear; (b) strong holding force; (c) long strokes and high resolution; (d) low noise; and (e) no generation of magnetic noise and no noise-influence.
As a conventional ultrasonic motor having these advantages, a linear ultrasonic motor wherein a movement part comprises two vibration boards, one guide shaft is held between the opposing parts of protruding parts which are formed, one on the opposing side of each of these vibration boards, and the movement part moves along the guide shaft by the vibration of the two vibration boards, is proposed. (For example, refer to paragraphs [0011] to [0012] and FIG. 1 of Japanese Patent Laid-Open Publication No. 09-051687.)
However, the technology in Japanese Patent Laid-Open Publication No. 09-051687 is prone to cause component to tilt in a plane formed by the driving direction of the guide shaft and the vibration boards with the driver protruding part as the fulcrum, because there is only one drive protruding part for each vibration board facing each other with the board in between.
In addition, the amplitude of the elliptical vibration at the protruding part functions to separate the vibration board and the guide shaft in the direction perpendicular to the guide shaft and enables relative driving of the guide shaft in the direction horizontal thereto. Drive is adversely affected if this tilting occurs because the elliptical vibration of said drive protruding part is optimized to achieve these functions.
If the tilting described above becomes too large, areas other than the drive protruding part, such as the vibration board and the guide shaft, come into contact. Vibrations in these areas generally work to inhibit the elliptical vibrations in the driving contacting part, and vibrations in a state of unnecessary contact may lead to destruction of the contacting parts.
Therefore, although it goes without saying that, first, a fixation component for fixing the guide shaft to the main body apparatus is necessary, engagement parts for the guide shaft is required in at least two locations in order to position the drive protruding parts to prevent tilting thereof to the guide shaft within the movement part. However, miniaturization of the entire configuration is difficult if there are many required configurations such as this.
Furthermore, in the configuration above, although it would appear that an attachment part is necessary to absorb error between the two, should a linear ultrasonic motor configured as such be applied to a drive wherein minor error is tolerated, for example a camera lens frame and the like, because the movement part is supported by the guide shaft without backlash, considerations such as this have not been made.